How does Harmony work?
 

Sometimes I cast it and seemingly nothing wrong happens, but then when I go to pull I end up getting aggro'd by the whole camp?

Played a warrior on live and I'm still trying to wrap my head around the mechanics of some things in the caster world :)

Basically nothing ever goes wrong with Harmony. Its unresistable, doesnt count as an aggressive action (you can harmony for others without taking faction hits), and it always works.

What you need to know is that it doesnt make mobs un-aggroable, it just lowers their aggro-radius. So if you pull one mob to close to another harmo-ed mob, you will get proximity-aggro.

Strategy:
Basically pick mobs of the "edges" of the group of mobs you want to separate, and navigate the pulls away from the group of mobs. Never aggro mobs that are behind other mobs when pulling with harmony, and you should be fine. As long as the mob you are pulling moves away from the other mobs it should never fail, except when mobs are to close to each other for harmony to ever work (still within aggro-radius of each other even with Harmony applied).

A sample of mobs that are to close to each other for harmony to work would be the two sisters in the same hut on sister island in OOT.

Does not always work. The cake is a lie, & etc. (Try it on yellow-con mobs sometime, I recommend Castle Mistmoore as your test venue.)

It doesn't always stick (can get resisted) but will never critical resist, resulting a pull.

I don't play a druid or ranger here, but unless it's different than live harmony has no resist check and can't be resisted.

Mobs have both a frenzy and a reaction radius. Frenzy radius is the range they'll aggro, and reaction is the radius they'll assist. Harmony reduces these to 15 for both. If you walk within 15 units of otherwise aggro mob who's harmonied they will attack. If that mob is within 15 units of another mob that it shares group aggro mechanics with, the other mob will assist. This limits harmony for closely packed mobs, but in many cases 15 is small enough that you can single pull them, especially if you make sure the mob you're pulling takes the path that keeps them the farthest away from other mobs.

It always sticks and it always lowers the radius around which mobs will agro and assist. However, for mobs with very large agro ranges (like Plane of Fear mobs, or raptors in TD) the radius could still be pretty big even after Harmony.

I don't want to come off sounding like some expert at this but this part of a thread I did on pulling. It does apply to Harmony also.

Every zone in EQ was designed by a different person or persons. So every mob in each zone behaves a little bit different. Think of mobs at a camp being on a string. They are all connected. What you do to one effects all of them. Some zones have bigger agro rates then others, some less. Very few mobs are un effected by the others in a camp. Caster mobs are the worse, and if they are in front best to pull them first. But very few are in front. EQ developers were pretty smart. So you need to first pull the trash mobs away, thinking about the string thing. Pull mobs that are at odd angles, and ones that are moving around in front first. Toy with them a bit and FD to see how they behave. No way you can ever pull the mob in the back first and get it only to come. Think of the string. I can't say it enough. Study the pathing. It will always repeat the same way every time in that camp. Pulling is the hardest thing to do well in EQ. It is a chess game. You can't just run in there and FD and hope one mobs stays. You can pull just about any mob single if you are good at it.

My son is the best puller I have ever seen in this game here and live. And he plays a Warrior and a Monk on both. He is scary good at pulling on a Warrior. He just knows what to do. Just remember the string thing lol. It takes tons of practice toying with them. You just have to remember each zone is a bit different. There is more to it then I have written, it is something I just do without really thinking about it. Hard to explain. But I was terrible at it at the beginning. Good luck.

I suggest in some cases using proximity pulling rather than attacking. Sidle up to the mob on the edge and let them agro from your presence. The assist radius on proximity pulling is smaller than pulling with a missile weapon.